(this page has been updated 22 November, 2011, in regard to using MKH 8020s in a SASS type of rig.)

more DIY lightweight stereo recording rigs

Having investigated budget-style SASS and binaural head designs (see page 'recording gear 1'), I wondered how best to obtain optimum quality recordings using a very low noise recorder coupled to lightweight, low-noise XLR mics in a lightweight foam rig of some sort.

the recorder:

Best results would come from using a Sound Devices 702 recorder which has less noise than the Olympus LS10.

lightweight professional-quality microphones:

Sennheiser MKH 8020 omnis are very lightweight and excellent quality mics, better sounding than MKH 20s and with less noise. An 8020 mic connected to an XLR plug is about the size of a large texta marking pen, and weighs not much more than an AA battery.

Are MKH 8020s suitable for SASS?

One drawback to the 8020s is that the mic element is set 5 mm inside the mic housing, rather than flush with the surface. Ideally, for SASS mounting the mic element needs to be flush with the boundary surface. However it has been pointed out to me that yes the 8020s will work in a flush mounted boundary.

This is my first attempt at a SASS type mounting for the 8020s. Preliminary tests indicate that the system will work fine. More tests to come ! (as at 22 November, 2011)

I also looked at other ways I could mount these 8020 mics. Binaural would work, so would Jeklin disk, so would various block-head and spaced-array designs.

Rob Danielson on the boundary mics group compared a larger version of his DIY SASS with the Olson Wing, both rigs using AT3032 mics, the results showed that the SASS design was a little more spacious sounding, with better localization and wider image. The stronger presence of the (lower pitched) owls and coyotes in the SASS version is partly due to larger surface of the SASS boundaries (approx. 10 x 10 inches, whereas a standard SASS boundary surface is approx. 5 x 4 inches.) But good localization and image width does seem to apply to all SASS recordings generally.

These are Rob’s sample recordings in mp3 format, recorded in the USA.

a. Olson Wing

b. Rob's SASS,

(there are several simultaneous sound samples.)

comparing the angle of the microphones using a rotateable foam Wing:

After listening to Rob's test, I wondered if I could improve on the Olson Wing to add some spaciousness.

If the mics were angled outwards, would this help to make the stereo image better? I experimented with angling the mics outwards, using a temporary Rotateable Wing and MKH 20 mics to compare parallel and angled positions. The angled position did give slightly better localization and width.

SOUND SAMPLES

Recording by Vicki Powys of Yellow Robins pre dawn, first 3 calls are parallel, next 3 calls are angled out (consecutive recordings rather than simultaneous). There is not much difference, but 2nd lot of calls have slightly better positional clarity.

1. parallel

2. angled

Here is another longer example, first 32 seconds are parallel, next 32 seconds are angled. Recordings are consecutive rather than simultaneous. There is a very slight but discernable difference, with the angled sound being more spacious when listening through headphones.

1. parallel

2. angled

Rotateable Wing vs SASS Lite:

Did the Rotateable Wing angled outwards at about 75 degrees now match the localization and image quality of the SASS?

I compared my SASS Lite with MKH20s angled outwards in the Rotateable Wing. The image of the angled wing was very good but still did not quite match that of the SASS. However, this will be the best match to the SASS that I can make.

Here are the two rigs in action:

SOUNDS

Simultaneous recordings by Vicki Powys. First half is the SASS Lite, second half is the angled wing - a bronzewing pigeon gives some low pitched calls and flies close to the microphones then lands behind the microphones, a thornbill gives high pitched alarm calls on the left. Other birds call in the background. Both renditions of the scene seem quite satisfactory to my ears.

1. SASS Lite

2. Angled wing

The Powys Angled Wing (PAW):

The PAW is a fixed version of the experimental Rotateable Wing. It is solid and compact and has the smaller dimensions of the Sennheiser 8020 mics in mind. Having the mics angled outwards is a compromise, designed to get the best from the 8020s and as near as possible to the spacious SASS imagery. The sound will also be brighter and have less noise than the test recordings made with MKH20s, due to inherent differences between these two microphones.

construction details of the PAW in progress - (still waiting on the faulty MKH 8020s to be returned by Sennheiser - 27 Oct. 2011 - NB the problem now seems to be solved, see 2012 update on this issue at the bottom of the next page 'recording gear 3'.)

Birdsong recorded by Vicki Powys, pre-dawn, November 2010. First you will hear the Knapp-modified SASS with MKH20s (diffuse field ON) for about 6 seconds, then the SASS Lite with twin EM172 capsules, continuing on with a number of short sequences compared.

Half the weight and very good quality is Belden mini star quad 1804A, available in Australia by the metre from Madison Technologies.

Neutrik for XLR plugs.

I find I need a minimum of 6 metres of cable to be able to stand back from the tripod and not have breathing or tummy rumbles intruding on the recording. Another solution is to leave the recorder at the tripod, and then walk further away.